普鲁士蓝膜修饰电极的电化学阻抗谱

Electrochemical Impedance Spectra of Prussian Blue Film Modified Platinum Electrode

测量了应用电化学方法制备的不同厚度的普鲁士蓝膜修饰电极的循环伏安行为与电化学阻抗谱.由所得到的循环伏安图讨论了普鲁士蓝修饰膜的氧化还原过程，并对相关的Nyquist图进行了解析，提出了相应的等效电路.在此基础上计算出较薄膜中普鲁士蓝/普鲁士白电化学反应的表观速率常数和表观扩散系数，讨论了膜厚度对电荷扩散的影响.当膜相对较薄时，电极过程主要由动力学过程控制；当膜达到一定厚度时，电荷在膜中的扩散速率受到限制，电极过程由动力学过程和电荷扩散过程共同控制，证实了文献报导的普鲁士蓝膜修饰电极为多层空间分布电荷传递模型.

Electrochemically fabricated prussian blue (PB) film modified platinum electrode was studied by cyclic voltammetric and electrochemical impedance techniques. The redox process of the modified layer was discussed with the observed CV plot. The measured impedance spectrum was analyzed and the corresponding equivalent circuit was proposed. The apparent charge-transfer rate constant and the apparent diffusion coefficient of PB redox couple within the modified layer were obtained. The dependence of impedance behaviors of the PB films on varied film thickness was systematically studied. When the modified layer was relatively thin, the apparent charge-transfer rate constant and apparent diffusion coefficient increased with the increasing thickness of PB film and the charge transfer process was enhanced obviously. The charge transfer process was predicted to be controlled by the kinetic factors. On the other hand, if the modified PB layer was comparatively thicker, the charge diffused with restricted rate, and would only reach to a certain distance inside the modified film. The results were well satisfied with the multilayer model of spaced distributed redox modified electrode found in literature.